First, I want to address your (the original poster’s) problem, since it was one I had for a while. You’re going to hate this advice, but I’m going to give it: keep writing. Keep chugging along, hopping from story to story. Eventually you’ll start one, and you’ll feel a little fire kindle in your chest. If you’re like me, every time you start a new story, you tell yourself ‘this is the one. this is the one i’ll finish. i know it this time’. But when you start this story, it will be rumbling in your chest, and you’ll start telling people about it, and you’re friends will get sick of the Chronicles of fill-in-the-blank, and you’ll make a wall-sized map, and it will sing to you.
This is a long-winded way of saying you haven’t found the right story yet. Keep having fun with different ideas, play around a little, let the words take you, come what may. You will find the right story–or, more truthfully, the right story will find you–eventually. That’s what happened to me. I’m on 21094 words right now, and the most I’ve ever written was ten-thousand something (and that…was bad…).
Of course, self-discipline is important too. I can’t tell you how many times I’ve been working on TCHC and have wanted to shift to some other epic journey. But I /love/ this one, and once you’ve found one you love, you can really keep firing at it, even when writers’ block sinks its teeth into your keyboard.
Once you start and finish that story, just keep writing. I can tell that, once you have the sufficient fire and self-discipline that staying focused on one story requires, then more will come.
My writing problems–well, the chief one was fixed with The Chronicles of [name]Herbert[/name] and Celwaithe (working title, don’t worry.) I found my story.
I tend to have problems with my villains. In TCHC, I started with a wonderful-ish villain, shifted to another villain who I don’t really love yet, and am contemplating turning protag’s love interest into the new villain. None of my villains are particularly hate-able either, which is unfortunate.
Another problem is that my characters don’t have distinctive voices. That’s bad. Very…very…bad. Needless to say. When I type, it sounds like one person is talking. However, that’s next-draft-fixable, so I don’t worry about it too much.